/*
 * Copyright 2022 emo Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.qhplus.emo.network

import kotlin.math.exp
import kotlin.math.ln

class ExponentialMovingAverage(private val decay: Float) {
    private var value = -1.0

    fun addMeasurement(measurement: Double) {
        value = if (value < 0.0) {
            measurement
        } else {
            exp((1 - decay) * ln(value) + decay * ln(measurement))
        }
    }

    fun getAverage(): Double = value

    fun reset() {
        value = -1.0
    }
}
